The invention relates generally to the discovery of cytokine receptors on microorganisms, and more specifically to new methods and products in medical treatment and research related to the discovery. Cytokines produced by monocytes/macrophages are called monokines, and those produced by lymphocytes are called lymphokines. Stimuli for their production include endotoxin and Gram-negative bacteria. One cytokine of particular interest is tumor necrosis factor .alpha. (TNF.alpha.).
TNF.alpha. is an inflammatory cytokine which has numerous biological activities and is believed to play important roles, not only in host defense but also in some of the pathological sequelae associated with bacterial infections. Receptor(s) for TNF.alpha. are found on most somatic cells, and they have recently been characterized and cloned. Biological effects of TNF.alpha. and other cytokines binding to eukaryotic cells are well known.
For example, it is now well established that cytokines play important roles in regulating aspects of the immune response. Cytokines have been shown to be essential for host defense against viruses, tumors and bacterial infections. There is, however, a delicate balance between when a cytokine is advantageous to a host and when it contributes to the pathology of a disease. Thus, knowledge of how to make the choice between administering a cytokine and blocking its action in a disease process could be a valuable tool in clinical medicine. The need for such knowledge is rapidly increasing as cytokines and cytokine blockers become more readily available.
Many cytokines have now been cloned and new cytokines are constantly being discovered and cloned. Recombinant cytokines are now also being used in clinical trials all over the world. Recently, much attention has been focused on identifying and cloning cytokine receptors on eukaryotic cells previously identified as being targets for the many cytokines produced by the immune system. But similar work on pathogenic cells such as bacteria has not been published; there are no reports of TNF.alpha. or any other cytokine binding to bacteria until quite recently (1A).